Although wearing of safety seat belts has proved to be effective protector for occupants in vehicles by restraining their bodies during emergencies, their unpopularity can be traced to the psychological aversion of the vehicle occupants to wear the belts by themselves and being restrained with straps. The mandatory usage of safety belts may be hardly accepted by most people, especially in the United States.
In order to solve this problem many passive safety systems, such as door-passive belts, air bags and elastic cushions have been devised but all of these systems, unfortunately, have their own defects.
A door-passive belt system requires installation of numerous complicated devices within the vehicle for lifting the belt synchronized with the movement of the door when occupants enter or leave the vehicle. This system not only requires longer belt and stronger retractor, or, additional retractors, but in some cases, belt guiding devices. Such additional complicated devices increase possibilities of failures, and worse, secondary collision injuries.
In an air-bag system the complete prevention of failure is difficult and protection against roll over accidents cannot be assured. Moreover, some propellants for air-bag inflation involve safety problems concerning installation, exchange or disposal, which will conflict with the legal reatrictions in some countries. In a cushion system, only the knees of an occupant seated in the front seat are protected. For complete protection for all occupants, a number of cushions have to be installed in all directions. Theoretically possible, but practical application has many problems. The existing cushion system, therefore, is supplemented with a belt system, usually lap belts, which must be adjusted manually. The aforementioned psychological aversion against belt or strap restraining will reduce its application.
Another type of vehicle restraint system consists of mechanical device which changes the position of the occupant or the occupant together with the position of the seat at the time of collision. For instance, M. Witter discloses a protective device in U.S. Pat. No. 2,943,866 filed Jan. 7, 1958 which comprises an upward raising means for the knees of the occupant to prevent the body from moving forward in collision by T-shaped raising means adapted to be mounted on a vehicle in front of the seat. It is believed, however, that the moving distance of the raising means cannot be large enough to protect the occupant in severe collision, or, for roll-over accident. A safety seat is proposed by M. Hartel in U.S. Pat. No. 2,736,566 filed Feb. 28, 1956, which could be said to be more effective than that of Witter's patent because the occupant is double up deeper, but Hartel's devised seat is believed not effective against roll-over accident. This mechanism, moreover, requires greater force to move the occupant together with the seat than moving the occupant alone.
Other types with movable seat system are disclosed by L. A. Woodsworth in U.S. Pat. No. 2,660,222 filed May 29, 1952, and by C. J. Lawrence in U.S. Pat. No. 2,823,730 filed Feb. 18, 1958. The former relates to a seat supported on a base by front and rear wheels. The plate supporting the rear wheels swings downward when the plate is unlocked by the action of pendulum weight tilting the seat rearward, while at the same time, the seat slides forward along the inclined track at the base. The latter movable seat system relates to a seat which is moved forward by momentum of the vehicle, while the frontal edge of the seat is moved upward by a brace, and the rear edge is moved downward from the disengaged hinged support.
Both of these systems require special construction of seats and vehicle body. Moreover, their effectiveness in roll-over accident is doubtful. Although a yoke-type or U-shaped lateral restraining member is disclosed respectively by Al Barsky (U.S. Pat. No. 2,796,112, filed Mar. 16, 1956) and L. B. Simon (U.S. Pat. No. 3,591,232, filed Apr. 1, 1969), these members are still not completely effective for lateral accidents, especially in the present trafic conditions of far higher speeds than those when these inventions were disclosed.
Many other safety devices have been proposed but all have their respective defects. A more simple, reliable and economical passive restraint protective system is urgently required. Especially, with the advent of speedier and efficient motor vehicles, the present invention provides the very system responding to these modern requirements.